A wide variety of fastening devices have been developed for joining the ends of conveyor belts together to form a continuous belt. Most of these devices are formed of metal. For may applications, however, it is desirable that the belt fastener be non-metallic. For instance, in the food industry there may be health codes or other regulations requiring metal detectors to detect the possible presence of metal particulate in the foods being carried by the conveyor belt. Metallic belt fasteners have been found to trigger the metal detectors which sense the metal fastener as it rotates with the belt, giving a false indication of the presence of metal in the food. Other food applications may involve foods which, for health concerns, must be prevented from contacting metal during all states of preparation. Metallic belt fasteners are undesirable for such applications. Furthermore, plastic belt fasteners are desirable for many non-food applications as well. An example of this is conveyor belts used in x-ray scanners at airports or the like.
An example of one prior art plastic belt fastener is found in British Pat. No. 1,261,681. The plastic belt fastener disclosed therein is undesirable in that at least one of the fastener plates are hinged by living hinge areas of reduced cross-sectional thickness to allow for bending thereat. Such plastic fasteners may break prematurely at the areas of reduced thickness of the hinge loops during normal operating loads. Also, the two plates of the fastener disclosed in the British patent are maintained clamped about the belt by a threaded engagement which has been found inadequate to withstand the separating forces imposed on the fastener during normal operation. The fasteners are formed with only a single hinge loop rather than the usual two loops in a metal hinge plate fastener. The bottom plate has upstanding bosses to receive projections from the upper plate and these bosses require larger holes in the belt, thereby weakening the belt. It is desirable to provide a non-metallic belt fastener which has sufficient strength to withstand normal conveyor belt loads.